You shouldn't need anything special on macOS. It works out of the box for me. Have you tried using it without being connected to a VPN? 1Password has its own encryption in addition to TLS, so security won't be an issue. I'm wondering if something is being blocked by the VPN service.

#> sudo dtruss ./op update
dtrace: system integrity protection is on, some features will not be available
SYSCALL(args) = return
You are running the latest version (0.5.5). Thank you for staying up-to-date!
dtrace: error on enabled probe ID 2198 (ID 557: syscall::sysctl:return): invalid kernel access in action #10 at DIF offset 28
[...]

So while using dtruss to analyse the process it somehow executes it different and responds properly.

Other commands like sudo op signing work but at the end it still does not possible to view items.
I tried another local userprofile on my machine op update works. So its appears to be something with my local profile. (I have no other problems with my machine)

What I noticed is that while I run op update when I checked the process hierarchy I found that /usr/bin/security processes are launched.
Doing ps aux | grep security while op update is running I see processes like:

@twx Is this a work machine — does your user profile have some special root/intermediary certificate authority configuration installed by your IT, maybe? When I connect to app-updates.agilebits.com:443 with openssl s_client to debug, I see:

it is a work machine. There are special certificates. All my colleagues do not have this problem.

However: I was able to fix it.
I think my solution is not something one should try out without knowing what this means.
So you have been warned: I have removed all entries from the "Certificates" folder from my Keychain.
And after a reboot everything works, update, signin, list 🎉

#> op update
You are running the latest version (0.5.5). Thank you for staying up-to-date!